1. Field of the Invention
This invention relates to a device for sealably enclosing a large diameter opening such as in a pipeline or a vessel, including an arrangement wherein the closure member is in the form of a relatively flat plate which can be removably positioned within the member to be closed and, when in the closed position, seals the opening in the member in a manner so that the entire closure member is within the interior of the flange.
The invention is particularly useful in closing a side opening in a pipeline under pressure in which hot tapping equipment is used to perform the opening or closing operation.
2. Description of the Prior Art
In the operation of pipelines it is frequently necessary to provide communication with the line without discontinuing service through the line. For this purpose "hot tapping" equipment is used. In this procedure, which is well known in the art, a branch line is first welded or bolted onto a pipeline. The branch line normally includes a flange at its outer end. Hot tapping equipment is attached to the flange which includes means of cutting a hole in the pipeline sidewall. A common procedure employed to repair a defective area of a pipeline without taking it out of service is to hot tap the pipeline to either side of the defective area. After the tapping is completed a bypass line is connected to provide a path for fluid flow while the defective portion is repaired.
Many other reasons exist for providing a side opening in a pipeline for temporary use. When such temporary use is completed it is necessary to close the side opening. A detailed description of the apparatus for and the methods of opening and closing side openings in pipelines is encompassed in U.S. Pat. No. 3,155,116 entitled: "Apparatus for Closing Side Openings Into Pipelines", Burton VerNooy patentee, issued Nov. 3, 1964, which patent is incorporated herein by reference. The present disclosure provides an improved plug or closure plate for closing an opening in a flange of the type described in this prior issued patent.